Life on a British bomber base, and the surrounding towns, from the opening days of the Battle of Britain, to the arrival of the Americans, who join in the bomber offensive. This movie centers around Pilot Officer Peter Penrose (Sir John Mills), fresh out of a training unit, who joins the squadron and experiences life during wartime. He falls for Iris Winterton (Renée Asherson), a young girl who lives at the local hotel, but he becomes disillusioned about marriage when the squadron commander dies in a raid, leaving his wife, the hotel manager, to bring up their young son alone. As the war progresses, Penrose comes to terms about surviving while others have been killed.